This invention relates to the art of gearshifting mechanisms and, more particularly, to improvements in manually operable gearshift mechanisms for shifting gears in a transmission.
It is of course well known that transmissions such as automobile transmissions provide a plurality of selectable gear combinations, and it is likewise well known that certain of such transmissions provide for the gears to be shifted from one combination to another through appropriate positioning of a pair of gearshift operators associated with the transmission and displaced relative to one another and to the transmission housing by generally linearly displaceable gearshift actuating cables. The latter cables are linearly displaced through the vehicle operator's manipulation of a manual gearshift mechanism in the vehicle and which includes a pivotal gear selector member for each cable. Upon pivotal displacement of the gear selector members relative to one another and to a common support therefor, the pivotal displacement of each member is translated to a linear displacement of the corresponding cable. In connection with the operation of an automobile, the gear combinations available include a neutral gear relationship, a reverse gear, and a plurality of forward drive gear ratios which today often include five forward drive gear ratios.
Examples of manually operable gearshift mechanisms heretofore provided for achieving such transmission gear changes are shown in U.S. Pat. No. 4,143,560 to Kinkade et al and U.S. Pat. No. 4,245,521 to Osborn. Mechanisms such as those disclosed in the latter patents, while effective for the intended gearshifting purpose, are structurally complex and thus both excessively heavy and undesirably expensive to produce. More particularly in this respect, the constructions have required the use of a number of interengaging component parts requiring close tolerances and finished surfaces involving time consuming and expensive machining operations and assembly operations. Moreover, such constructions are undesirably heavy as a result of the number of component parts and the size and weight thereof and, additionally, are undesirably large with respect to the outside dimensions thereof. Furthermore, structurally complex arrangements for translating motion within the gearshift mechanisms and for providing lockout with respect to unintentional shifting into the reverse positions thereof, have added to the cost and weight of the mechanisms while at the same time rendering the efficiency and stability with respect to the operation thereof less than is desired.